All else being equal it does. There are other differences in the two cartridges, the main one being the throat length which can have a significant effect on pressure.

My books ( Sierra , Hornady ) Sierra is loading with the same components and Hornady has different brass and maybe primers but both books say the 223 gets the same or heavier charges then the NATO round . With the NATO throat being longer I would have thought the NATO round would be able to take the heavier charge .

I'm not implying anything just looking at the numbers and want to understand . That's why I was asking if it's all about the twist and if that increases or decreases pressure . Maybe factory NATO ammo is hotter then what the books recommend to load .

Your right kraigwy I have all kinds of questions and or statements and I see how this thread would get derailed very fast . Sorry I'll stop

__________________As of this date 8-18-14 at 6:42am I became a proud grandfather I guess I'm officially old
I hear Glock just came out with a new pistol . I hear it's a tribute to the senate and the house of representatives . It's called the congressman . It hardly ever works and can't be fired .